System for renovating a sewer manhole

ABSTRACT

A method for renovating a sewer manhole includes: a. pulling an inflatable film sleeve onto a mold corresponding to the sewer manhole profile; b. wrapping and/or laying an extensible textile strip of the film sleeve onto the mold, a non-extensible high-tensile-strength longitudinal strip also being laid in an axial direction between the strips; c. attaching a protective sheath enclosing the liner manufactured in this manner; d. pulling the liner off the mold that has been reduced in a radial direction; e. inserting the liner into a sewer manhole to be renovated, and introducing a pressure-tight bag into the inner film sleeve of the liner; f. sealing the liner at the upper end and inflating until it abuts against the manhole wall; g. curing the resin-impregnated liner. A variable mold, which is assembled from modules of different shapes and sizes corresponding to the sewer manhole, serves for manufacture of the liner.

FIELD OF THE INVENTION

The invention relates to a method for renovating a sewer manhole by means of a liner, to a liner manufactured using the method, and to an apparatus for manufacturing the liner.

BACKGROUND OF THE INVENTION

Sewerage systems, in particular manholes, are subject to a very wide variety of thermal, chemical, and hydrological stresses. Trades and industry, among others, make a substantial contribution to high operational stress. Dairies, breweries or the chemical industry in general, for example, introduce considerable quantities of particularly aggressive substances that, by themselves or by admixture with further incoming substances, initiate chemical reactions while flowing.

This contaminant load, in combination with high energy levels in the wastewater (turbulent flow due to high wastewater inflow, for example after flooding), has a highly abrasive effect over time. Ongoing surface corrosion of structures ultimately results, over a period of years, in massive damage to the supporting material. Substantial cracks are sometimes produced in the structure, often occurring e.g. at the joins between the manhole rings. On the one hand, an ever-increasing volume of dirty water leaks through the cracks out of the sewerage system into the environment, with correspondingly negative consequences; on the other hand, outside water also seeps in, for example if the groundwater level rises, putting an additional load on treatment plants. Both phenomena constantly promote corrosion. Sewer systems exhibiting these types of damage represent a considerable hazard and urgently require renovation.

A variety of methods are known from the existing art for renovating sewer systems, in particular manhole structures:

Plastering with cement-based coating materials may be identified as a fairly classic method, but permanent durability is lacking here. The use of reaction-resin coatings is also problematic because the coating can form bubbles and detach from the substrate. It is possible to seal the surface using coatings and thereby protect a structure, but the load-bearing capacity and static strength of the structure are not restored by a thin layer of cement or resin.

It is therefore also known to line a sewer manhole with pipes or curved plates that are manufactured from glass-reinforced plastic (GRP). GRP materials of this kind are notable for high- and low-temperature strength, dimensional stability, and chemical resistance. Parts made of thermosetting plastic represent a suitable material for renovation because they are insensitive to acid and to similar aggressive substances, especially since components having large wall thicknesses and complex geometries, along with high compressive strength, can be manufactured. It is disadvantageous, however, that preparation of the plates to be fitted in is complex, and that pipes cannot readily be installed into existing sewerage systems.

A further method therefore provides for introducing a tubular “inliner” into a sewer system, pressing it against the sewer wall with compressed air, and lastly curing it with a UV light source. DE 39 22 351 A1 describes for this purpose a method for renovating drainage pipes using a resinified inner pipe that is introduced in an axial direction into the relevant sewer segment, unfolded by an expandable bladder, and then cured. DE 43 26 503 C2 discloses the manufacture of a tubular lining sleeve of arbitrary length. Such a sleeve is unsuitable for branches and sewer manholes, however, in particular manhole necks, especially since the latter in most cases taper conically. DE 197 02 649 Al deals with the sealing of branch pipes with the aid of an additional sealing member on an inliner, in order to bring about sealing of the connecting channel with a renovation packer. This method as well, however, is unsuitable for sealing a sewer manhole.

The subject matter of DE 699 25 045 T2 is a lining device for sealing and reinforcing the walls of a manhole using a sleeve that is assembled from at least three plies, which are joined to one another by seams and of which the center ply seals the liner.

DE 10 2009 050 084 discloses a multi-layer sleeve as well as a method for manufacturing it, which can be used for the renovation and lining of pipelines. The sleeve is continuously manufactured at a constant diameter, for which purpose a flat film is welded at its overlapping longitudinal edges and then drawn through an assembly tube. Simultaneously, longitudinal strips impregnated with resin are laid onto the assembly tube; these are pulled off together with the inner sleeve formed by the flat film, and are intended to connect to one another behind the tube end.

Lastly, DE 697 02 876 T2 describes and depicts a plastic liner for a manhole and a method for coating it. Here the liner is made up of a pouch, initially applied in a flat shape, that is inflated after introduction into the manhole, although crumpled areas and creases in conical transition segments are unavoidable.

SUMMARY OF THE INVENTION

The object on which the invention is based is to describe a system for renovating a sewer manhole in order to achieve the following objectives:

-   -   sealing leaks,     -   creating a physically and chemically resistant surface that can         readily be cleaned,     -   improving the stability of the manhole, in particular in the         region of ladder rungs.

According to the invention the features of a method and apparatus as described hereinafter serve respectively to achieve this object. Advantageous refinements are also described.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained below with reference to exemplifying embodiments that are depicted in the drawings, in which:

FIG. 1 is a schematic longitudinal section of a sewer manhole;

FIG. 2 is a perspective depiction of a mold during the wrapping and laying of a liner in accordance with the invention;

FIG. 3 shows various modules for use in an apparatus according to FIG. 4;

FIG. 4 is a schematic sectioned depiction of an apparatus for manufacturing a manhole liner in accordance with the invention;

FIG. 5 shows a possible cross section in plane V-V of FIG. 4;

FIG. 6 shows a wrapping apparatus for use in the apparatus of FIG. 4;

FIG. 7 is a schematic depiction during the introduction of a liner into a sewer manhole;

FIG. 8 shows the liner depicted in FIG. 7 in the expanded final state;

FIG. 9 schematically depicts a fastening apparatus for ladder rungs;

FIG. 10 is a plan view of a lined manhole;

FIG. 11 is an enlarged depiction of a portion of FIG. 10;

FIG. 12 shows the routing of leads to a device;

FIG. 13 shows the introduction of leads through the back side into the device;

FIG. 14 shows the introduction of leads through the outer side into a device;

FIG. 15 shows a variant of FIG. 12 having a routing conduit;

FIG. 16 is a view of the routing conduit of FIG. 15;

FIG. 17 is a view of a sector of a mold having push-through pegs for fastening ladder rungs;

FIG. 18 is an enlarged depiction of a push-through peg in accordance with FIG. 17;

FIG. 19 is a cross section through part of the mold, of the liner, and of a fastening plate for a ladder rung; and

FIG. 20 shows a portion corresponding to FIG. 19, after expansion and curing of the liner in the manhole and fastening of a ladder rung.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 shows by way of example a sewer manhole 10 as defined in DIN V4034-1:2004-08. Sewer manholes of this kind have an eccentric cone 12 that sits on cylindrical barrel sections 14 which are positively connected to one another. Located in lower manhole part 16 is a step (berm 18) into which is recessed a gutter 24 that creates the connection to a sewer pipe 22. Sitting on eccentric cone 12 as the upper termination of manhole 10 is a manhole covering 26 made up of a frame 28 having support rings 30 and a cover 32. Support rings 30 allow adjustment to grade. Once cover 32 has been lifted, it is possible to climb down to step 18 at the bottom of the manhole via ladder rungs 36 mounted on the cylindrical manhole wall 34.

Sewer manholes 10 often deviate from standardized stipulations. A very wide variety of configurations exist both in the region of eccentric cone 12 with its conical transition, and in the lower manhole part having berm 18. The manufacturing method provided in accordance with the invention allows both standard shapes and almost all special shapes to be lined.

FIG. 2 shows the embodiment of a mold 38, provided in accordance with the invention and arranged horizontally, for wrapping and laying a manhole liner 50 (FIGS. 7 and 8) that reproduces the inner surface of sewer manhole 10 but whose diameter is smaller by a specific dimension in order to take into account the thickness of manhole liner 50 and the clearance necessary therefor upon introduction into manhole 10. Mold 38 is manufactured as a hollow member, for example from sheet metal that is assembled from a variety of modules in accordance with the shape of the manhole and is used in an apparatus 20 indicated in FIG. 4. The example of FIG. 3 shows a number of different modules 38-1, 38-2, 38-3.

FIG. 4 schematically depicts apparatus 20 for receiving, with rotary drive, a mold 38 with which a liner 50 in accordance with the invention can be manufactured. Extending from a column 42 is a horizontal axle 100 that is fastened nonrotatably on column 42 and on which a drum 102 is mounted rotatably via rolling or plain bearings 104. A controllable-speed motor 106, which is attached to column 42 and whose shaft 108 imparts rotation to drum 102 via a gearbox 110, serves to drive drum 102. A pneumatic or hydraulic drive is alternatively also conceivable.

As already mentioned, mold 38 is embodied as a hollow member that is assembled from juxtaposed modules whose dimensions (length, diameter, taper angle) correspond to the shape of the manhole to be lined. The example depicted shows a large cylindrical module 38-1 for lining the vertically superimposed barrel sections 14, the length of which module corresponds to the manhole depth in the cylindrical region upwardly adjacent to berm 18 (see FIG. 1) and is generally a multiple of the diameter. The subsequent module 38-2 serves for manufacture of the liner segment for eccentric cone 12, which is followed by a small cylindrical module 38-3 to terminate the cone. As shown in FIG. 4, the juxtaposed modules 38-2, 38-3 are connected nonrotatably to the closed end of drum 102 via positive coupling elements 112.

Liners for other manhole cross sections can of course also be produced, for example by combining different modules or by means of polygonal modules 38-1′.

FIGS. 4 and 5 indicate the possibility of subdividing at least the large module 38-1 into two or in this case four circle segments 118, so that the diameter can be modified. Each segment 118 is mounted, by means of at least one radially inwardly protruding foot 120, in a guide 122 that projects from drum 102. This allows segments 118 to be steplessly displaced in a radial direction in the direction of the arrows shown, for example at a 2:3 ratio (see FIG. 5), to enable at least two adjacent nominal diameters to be generated.

In order to close the gaps between segments 118 in the radially extended state, arc-shaped bridging elements 124 that are pivot-mounted at one end 126 on the adjacent segment 118 can be provided. Radial displacement of segments 118 can occur in motorized fashion; this is not depicted further.

Mold 38 is mounted in cantilevered fashion on axle 100 via drum 102. Its right-hand end (in FIG. 4) is thus free and can be adapted, for production of the variously embodied liners 50, to the shape respectively existing in the region of eccentric cone 12.

FIG. 2 schematically shows the method for manufacturing liner 50 with the aid of mold 38. Firstly an inflatable film sleeve 40 (FIG. 7) is pulled onto mold 38, the purpose of said sleeve being to protect mold 38 from adhesive so that liner 50, once produced, can ultimately be pulled off. Film sleeve 40 is feathered in the tapered cone region, i.e. notched from the free end in a longitudinal direction, whereupon the overlaps resulting therefrom are adhesively bonded from the outside. It is also possible to fit prefabricated cut pieces of film onto one another.

A laterally arranged wrapping apparatus 130, indicated in FIG. 6, carries rolls 44 of an extensible textile strip 46, as a rule made of glass-fiber material, that enables mold 38 to be wrapped at different angles of inclination with respect to the axis of mold 38. In the example of FIG. 6, wrapping apparatus 130 has a carriage 132 that carries a roll 44 and is movable back and forth relative to apparatus 20 in a longitudinal direction in the direction of arrow W of FIG. 4.

Additionally or alternatively, extensible textile strips 46′ can also be laid axially in a longitudinal direction. These are embodied in FIG. 2 as narrow bands; it is also possible instead to use wide strips 46′ of which one, two, or three respectively cover somewhat more than the circumference of mold 38. In a context of multiple plies, the overlaps are offset from one another in a circumferential direction in order to largely preclude accumulations of material.

Axially arranged longitudinal strips 48, non-extensible and therefore having high tensile strength, ensure that the composite produced is cohesive in an axial reaction and holds together against the weight of liner 50 upon installation in manhole 10. The high-tensile-strength longitudinal strips 48 can be guided out via the tapered neck portion in order to facilitate suspension of the completed liner 50 and introduction into sewer manhole 10. Precut textile pieces 98, whose shape corresponds to the tapered surface of eccentric cone 12, can be incorporated into the wrapping in the region of the tapered eccentric cone 12.

Strips 46, 46′, and 48, and cut pieces 98, overlap one another to yield a dimensionally stable composite for liner 50. The wall thickness can be different at different manhole depths so as to adapt to different applied loads.

Once the above-described composite for liner 50, whose strips 46, 46′ and cut pieces 98 have been respectively wrapped or laid dry or preferably wet, i.e. impregnated with resin, has been completed, said composite is surrounded with an outer protective sheath 52 that is made of webs of a thicker film made of sealing, UV-opaque material, for example a composite film of polyamide and polyethylene. The webs for this protective sheath 52, which are as wide as possible in order to minimize overlaps, are wrapped in a circumferential direction around the composite, after which the overlaps are covered with adhesive tapes. The mechanically robust protective sheath 52 ensures that liner 50 is a high-strength, one-piece GRP composite, and forms a barrier layer against the penetration of liquids and gases into sewer manhole 10.

FIG. 11 indicates that a metal band 55 that is preferably made of an aluminum adhesive tape can be applied axially onto the outer side of protective sheath 52 at 0°, i.e. at the point where, with liner 50 in the vertical installation position, the perpendicular is continuous from bottom to top and is not interrupted by the taper of eccentric cone 12. This band allows the wall thickness of liner 50 to be checked after curing, at every manhole height, with an eddy current meter.

It is evident from FIG. 4 that the diameter of mold 38 can be made slightly smaller, for which purpose segments 118 are displaced radially inward so that the completed GRP liner 50 can be stripped off in an axial direction over the free end of mold 38 (indicated with dashed lines).

FIG. 7 shows the introduction of GRP liner 50 into sewer manhole 10. Firstly, a plate 54 that fills up the manhole cross section is mounted at the lower end of liner 50 as a working platform and assembly aid. Fastening panels 56 can then be temporarily fastened on manhole wall 34, for example by adhesive bonding 82, in the pattern of a two-row or single-row arrangement of ladder rungs 36 to be installed later (see FIG. 9). A circumferential, permanently elastic seal 60 is mounted on manhole wall 34 just above berm 18 (in the case of concrete manholes, below the lowest joint 58 between the lowest barrel section 14 and berm 18). This seal creates sealing between manhole liner 50 and manhole wall 34. A pressure-tight bag 66 is inserted into the inner film sleeve 40; into this will then be lowered, via a hauling rope 78, a disk 62 that, in the final lowest position, abuts on plate 54 at the step (berm) 18 when GRP liner 50 has assumed its intended position in manhole 10.

The upper end of bag 66 is closed off in pressure-tight fashion with a cover 64. The latter has a connector 68 for introduction of a medium under positive pressure, preferably compressed air, so that bag 66 can be inflated. Cover 64 furthermore has an opening 70 for the introduction of thermal energy, preferably via a cable 72 for powering a UV or infrared radiation source 74, and optionally a further opening for a cable that leads to a digital camera.

GRP liner 50 that has been prepared for installation is then suspended from a hoist 76 and lowered into sewer manhole 10 so that its shape coordinates with the shape of the manhole in terms of vertical and rotational position. Bag 66 is then expanded by positive pressure so that GRP liner 50 unfolds and abuts tightly against manhole wall 34, against sealing ring 60 at the lower end, and against fastening panels 56. The force acting on disk 62 as a result of the positive pressure is braced by plate 54. The compressive force acting on cover 64 is absorbed by lower disk 62 via hauling rope 78 that extends axially through bag 66, and disk 62 arrives at a centered location inside manhole 10. Radiation source 74 for curing GRP liner 50 is switched on and is moved up and down by means of its power cable 72 along hauling rope 78 until liner 50 is cured. Radiation source 74 moves approximately in the center axis of the liner so that uniform curing at all locations is ensured.

When GRP liner 50 is cured, the positive pressure is released and radiation source 74 is switched off. After the removal of cover 64 along with radiation source 74, lower disk 62 and bag 66 can be pulled out with the aid of hauling rope 78, and plate 54 can be removed. Film sleeve 40 is also taken out. The ends of liner 50 projecting at the top and bottom, and outer protective sheath 52, are then detached.

FIG. 7 shows the renovated sewer manhole 10 with the final liner 50.

There are several possibilities for fastening ladder rungs 36. According to FIG. 9 the attachment locations on the inner surface of GRP liner 50 are marked using the same dimensions that were previously used when attaching fastening panels 56. Fastening holes for ladder rungs 36 are then drilled into fastening panels 56. Ladder rungs 36 can be fastened using bolts and cap nuts 80 that are attached behind fastening panels 56. Fastening panels 56, which are covered by liner 50, can be equipped with a small permanent magnet 128 for localization thereof.

One alternative is the possibility, indicated in FIG. 11, that instead of fastening panels 56 between manhole wall 34 and liner 50, fastening plates 53 having an internal thread are incorporated during the manufacture of liner 50 between the latter and outer protective sheath 52. This explained later on with reference to FIGS. 17 to 20.

The advantages of fastening ladder rungs 36 to liner 50 are the following:

-   -   a) no anchor holes in manhole wall 34 which would produce         leakage points;     -   b) manhole walls 34 that are already damaged are not weakened in         terms of their load-bearing capacity;     -   c) fastening onto liner 50 ensures long-term load-bearing         capacity.

Measurement devices, control devices, and other devices 84 are increasingly being mounted in sewer manholes 10. The cables and leads 86 connected thereto are usually routed along manhole wall 34, where they interfere with cleaning.

According to a refinement of the invention in accordance with FIGS. 12 to 15, leads 86 can be routed in the space between liner 50 and manhole wall 34, so they cannot interfere with cleaning or be damaged in the course of work in manhole 10. As already shown by the fastening of ladder rungs 36 in FIG. 9, devices 84 are bolted onto fastening panels 56. The use of cap nuts 80 also means that the drilling pattern for fastening them need not be determined until later.

Cable passthroughs can also be attached later. Cables 86 are usually guided in protective pipes 88 in the ground to manhole 10. There an orifice 90 of sufficient size is introduced into manhole wall 34 using a core drill. Flexible plastic insulating tubes 92, or dimensionally stable but flexurally soft plastic conduits 94 (FIG. 16), lead from orifice 90 on the inner surface of manhole wall 34 to fastening panel 56. They are at first provisionally fastened onto manhole wall 34 by adhesive bonding 82.

In principle, hoses rather than electrical leads 86 can also be routed in this manner. The diameters of insulating tubes 92 or the dimensions of cable conduits 94 encounter limits in terms of the strength of GRP liner 50, and must be designed in accordance with local forces.

When liner 50 has been installed, it conforms against fastening panels 56 and against insulating tubes 92 or cable conduits 94, and secures them in their final position. The passthrough for leads 86 through the manhole liner to device 84 must be sealed using cable fittings. Orifice 90 in manhole wall 34 must be closed off with assembly foam 96 until it is used for leads 86. Assembly foam 96 can easily be removed before leads 86 are routed. After routing, orifice 90 can be sealed again in the same manner.

The refinements depicted in FIGS. 12 to 16 have the advantage that the supply lines are routed behind manhole liner 50 made of GRP. In addition, anchor holes in manhole wall 34, and thus possible leakage points, are avoided.

FIGS. 17 to 20 show one possibility for manufacturing the fastening system for ladder rungs 36, as indicated in FIG. 11. There ladder rungs 36 are bolted not onto fastening panels 56 as shown in FIGS. 12 to 14, but instead onto fastening plates 53 of approximately square shape having edges 57 that taper in beveled fashion.

FIG. 17 depicts a circle segment of mold 118 on which push-through pegs 63 are placed in pairs corresponding to the intended arrangement of fastening bolts 73 for ladder rungs 36. Upon manufacture of the textile composite for liner 50 on mold 118, these pegs 63 generate holes 67 that serve for subsequent reception of embedded nuts 80 that are part of fastening plates 53. Once the textile composite is complete, push-through pegs 63 are removed outward from their latched engagement or, carried by an apparatus, they are countersunk together below the support surface of mold 38.

FIG. 18 shows an example of a push-through peg 63 that can alternatively have a rotationally symmetrical tip 65 or an oblique tip 65′. Sockets 61, into which shank 114 of push-through peg 63 latches with the aid of a spring washer 116, are fastened in mold 38. The desired rotational position of peg 63 having an oblique tip 65′ can be adjusted via a slot 115 in shank 114. Located in tip 65, 65′ is a transverse orifice 117 for insertion of a tool with which peg 63 can be pulled out again once liner 50 is complete.

In order to convey into liner 50 the forces occurring on ladder rungs 36, fastening plates 53 are made of synthetic resin, for example GRP, into which two respective nuts 80 are embedded. Fastening plates 53 are placed onto the textile composite of liner 50 in such a way that projecting parts 69 of nuts 80 penetrate into holes 67. Then, as indicated in FIG. 17, fastening plates 53 are temporarily secured with adhesive tapes 71. Lastly, as already explained, liner 50 is covered with a protective sheath 52 that, in this method, does not need to be perforated for fastening ladder rungs 36.

Once liner 50 has been inserted into manhole 10, ladder rungs 36 are fastened using threaded bolts 73 that are screwed into embedded nuts 80 (see FIG. 20).

The invention makes available a system whose essential advantages are described below:

-   -   1. Liner 50 is a one-piece shaped part that extends from manhole         cover 32 to just above berm 18, and reproduces the shape of         manhole 10.     -   2. The composite material is preferably made of glass-fiber         material impregnated with resin, having the following         properties:     -   excellent sealing with respect to gases and liquids;     -   mechanically and chemically strong, also (with appropriate         materials) resistant to aggressive chemicals;     -   smooth surface that can be effectively cleaned;     -   long service life.     -   3. Protective sheath 52 of liner 50 is arranged on the outer         surface.     -   4. Liner 50 can have different wall thicknesses in various         regions, corresponding to locally different loads.     -   5. Manholes 10 having reduced strength can be re-stabilized with         liner 50.     -   6. The invention makes possible a technology for fastening         ladder rungs 36 and devices 84 on liner 50.     -   7. The invention allows leads 86 and the like to be routed in         the space between manhole wall 34 and liner 50. 

The invention claimed is:
 1. A method for renovating a sewer manhole comprising the following steps: a. pulling an inflatable film sleeve (40) onto a mold (38) corresponding to a sewer manhole profile, b. wrapping or laying at least one extensible textile strip (46, 46′) of the film sleeve (40) pulled onto the mold (38), at least one non-extensible high-tensile-strength longitudinal strip (48) also being laid in an axial direction between the extensible textile and non-extensible strips (46, 46′), c. attaching a protective sheath (52) enclosing a liner (50) manufactured in this manner, d. pulling the liner (50) off the mold (38) that has been reduced in a radial direction, e. inserting the liner (50) into a sewer manhole (10) to be renovated, and introducing a pressure-tight bag (66) into the film sleeve (40) disposed inside of the liner (50), f. sealing the liner (50) at an upper end and inflating until the liner abuts against a manhole wall (34), and g. curing the liner (50) impregnated with resin.
 2. The method according to claim 1, wherein a metal band (55) is applied in a longitudinal direction onto an outer side of the protective sheath (52).
 3. The method according to claim 1, wherein upon manufacture of a textile composite in accordance with step b., textile cut pieces (98) are incorporated in order to cover non-cylindrical shaped parts.
 4. The method according to claim 1, wherein, in order to manufacture the protective sheath (52), wide webs of a thicker film made of a UV-opaque material, which overlap at their edges, are laid in a circumferential direction onto the liner (50).
 5. The method according to claim 3, wherein the textile strip (46, 46′) and cut pieces (98) are made of a glass-fiber material.
 6. The method according to claim 1, wherein the liner (50) is produced in a position rotating around a horizontal axis.
 7. The method according to claim 3, wherein the textile strip (46, 46′) and cut pieces (98) either are applied dry and then impregnated with resin, or are applied having just been impregnated with resin.
 8. The method according to claim 1, wherein in order to cure the liner (50), a source (74) of IR or UV radiation is introduced thereinto from above and is moved back and forth therein along a center axis.
 9. The method according to claim 1, wherein for fastening ladder rungs (36) or devices (84), fastening panels (56) are inserted between the liner (50) and the manhole wall (34), or fastening plates (53) having embedded nuts (80) are inserted between the liner (50) and the protective sheath (52).
 10. The method according to claim 1, wherein a sealing ring (60) is inserted between a lower end of the liner (50) and the manhole wall (34).
 11. A liner (50) for sewer manholes (12) to be renovated, manufactured using a method according to claim
 1. 12. An apparatus for manufacturing a liner (50) according to claim 1, wherein the apparatus is made up of a variable mold (38) that is assembled from modules (38-1, 38-2, 38-3) of different shapes and sizes in accordance with a sewer manhole (10) to be renovated.
 13. The apparatus according to claim 12, wherein the modules are mounted on a drum (102) that is driven rotatably around a horizontal axis.
 14. The apparatus according to claim 13, wherein the drum (102) is mounted in cantilevered fashion on a stationary axle (100).
 15. The apparatus according to one of claim 12, wherein at least one of the modules (13-1) is assembled from circle segments (118) that are radially displaceable in order to modify diameter.
 16. The apparatus according to claim 15, wherein adjacent circle segments (118) are connected to one another by arc-shaped bridging elements (124). 